Preparation of enol ethers by carbonyl olefination utilizing an alkoxymethyl chloride-titanocene(II) system

Aldehydes, ketones, esters and lactones are transformed into enol ethers or 1,2-dialkoxy-1-alkenes by treatment with organotitanium species prepared from alkoxymethyl chlorides and a titanocene(II) complex.     

Tris(pentafluorophenyl)silyl enol ethers: synthesis and aldol reactions

Silyl enol ethers bearing three pentafluorophenyl groups at the silicon atom are described. These compounds undergo uncatalyzed aldol reactions with aliphatic, α,β-unsaturated, and aromatic aldehydes. The observed reactivity is analyzed in terms of the Lewis acidity of the silyl fragment.     

3-氨基-2-吡啶酮互变异构的密度泛函理论计算

采用密度泛函理论,在B3LYP/6-3 l1G**基组水平上,计算并考察了3-氨基-2-吡啶酮分子酮式和烯醇式结构进行结构互变的质子迁移过程中的2种可能途径:(a)分子内质子迁移,(b)水助质子迁移.计算结果表明,途经b所需要的活化能较小,氢键在降低反应活化能方面起着重要作用.     

1H and 13C NMR study of 5-substituted-4- (arylidene)amino-2,4-dihydro-3H-1,2,4-triazole-3-thiones and 6-aryl-3-(D-gluco- pentitol-1-yl)-7H-1,2,4-triazolo[3,4-b] [1,3,4]thiadiazines

Five 5-substituted-4-(arylidene)amino-2,4-dihydro-3H-1, 2,4-triazole-3-thiones (2a-2e) and seven 6-aryl-3-(D-gluco-pentitol-1-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines (3a-3g) were synthesized. The complete 1H and 13C NMR chemical shift assignments were analyzed on one- and two-dimensional NMR techniques, including DEPT, NOE-DIF, COSY, gHMBC, and gHSQC.     

3-羟基哒嗪及其CH3, NO2和Cl取代衍生物质子转移过程的理论研究

用密度泛函理论(DFT) B3LYP方法, 在6-311＋G*基组下, 对3-羟基哒嗪及其CH₃, NO₂和Cl取代衍生物分子醇式和酮式结构互变异构化反应进行了研究, 优化化合物的几何构型, 寻找反应的过渡态, 通过振动分析和内禀反应坐标(IRC)分析加以证实, 计算了反应的活化能. 结果表明, 3(2H)-哒嗪酮及其带取代基的衍生物不论是单体, 还是相对应的二聚体, 比其相对应的异构体能量低, 表明在通常情况下是以3(2H)-哒嗪酮及其衍生物形式稳定存在的, 这与前人通过实验数据对3-羟基哒嗪互变异构体的比率进行预测的结果是一致的. 根据计算结果讨论了异构化反应的机理.     

Dehydrohalogenation of isomeric 2- and 3-bromomethyl substituted 2,3-dihydrooxazolo[3,2-a]pyridines

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Design and Enantioselective Synthesis of Cashmeran Odorants by Using “Enol Catalysis”

Novel Cashmeran odorants were designed by molecular modeling. Their short syntheses involve a novel asymmetric Brønsted acid catalyzed Michael addition of unactivated α‐substituted ketones. This key transformation was realized by utilizing a new type of enol activation catalysis and affords different cyclic ketones bearing α‐quaternary stereocenters in good to excellent yields and with high enantioselectivity. Subsequent McMurry coupling and Saegusa–Ito oxidation furnished the enantiopure target odorants, one enantiomer of which indeed possesses the typical olfactory aspects of Cashmeran.     

Scalable Synthesis of the Potent HIV Inhibitor BMS‐986001 by Non‐Enzymatic Dynamic Kinetic Asymmetric Transformation (DYKAT)

Described herein is the synthesis of BMS‐986001 by employing two novel organocatalytic transformations: 1) a highly selective pyranose to furanose ring tautomerization to access an advanced intermediate, and 2) an unprecedented small‐molecule‐mediated dynamic kinetic resolution to access a variety of enantiopure pyranones, one of which served as a versatile building block for the multigram, stereoselective, and chromatography‐free synthesis of BMS‐986001. The synthesis required five chemical transformations and resulted in a 44 % overall yield.     

Zirconyl Chloride Promoted Highly Efficient Domino Synthesis of New 1, 2, 3, 4-Tetrahydroquinoline Derivatives in Water

The tetrahydroquinoline moiety is present in various natural products, and many tetra- hydroquinoline derivatives exhibit a broad range of biological activities1. Therefore, it has attracted continuous interest to develop methods for the synthesis of tetr…     

4-Hydroxy-2-quinolones. 93. Synthesis and biological properties of 2-hydroxy-4-imino-1,4-dihydroquinoline-3-carboxylic acid N-R-amides

Various methods of synthesizing amides of 2-hydroxy-4-imino-1,4-dihydroquinoline-3-carboxylic acids have been studied. Results of investigations on the antitubercular and antiinflammatory activity of the obtained compounds are discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 542–555, April, 2006.